I’m currently using the Fmod - Unity integration version 1.05.08, and when I’m monitoring the audio coming from Unity to Fmod Studio I only get a stereo output on the Master Bus, instead of a surround output like I would get if I previewed the events inside Fmod Studio.
The mixer buses will default to however many channels the system can output. You can force the mix to a specific format, and let a down-mix happen at the very end.
Try adding this to FMOD_StudioSystem.cs at line 281